/**************************************************************************
***    
*** Copyright (c) 1995-2000 Regents of the University of California,
***               Andrew E. Caldwell, Andrew B. Kahng and Igor L. Markov
*** Copyright (c) 2000-2002 Regents of the University of Michigan,
***               Saurabh N. Adya and Igor L. Markov
***
***  Contact author(s): abk@cs.ucsd.edu, imarkov@umich.edu
***  Original Affiliation:   UCLA, Computer Science Department,
***                          Los Angeles, CA 90095-1596 USA
***
***  Permission is hereby granted, free of charge, to any person obtaining 
***  a copy of this software and associated documentation files (the
***  "Software"), to deal in the Software without restriction, including
***  without limitation 
***  the rights to use, copy, modify, merge, publish, distribute, sublicense, 
***  and/or sell copies of the Software, and to permit persons to whom the 
***  Software is furnished to do so, subject to the following conditions:
***
***  The above copyright notice and this permission notice shall be included
***  in all copies or substantial portions of the Software.
***
*** THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, 
*** EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
*** OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. 
*** IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
*** CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT
*** OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR
*** THE USE OR OTHER DEALINGS IN THE SOFTWARE.
***
***
***************************************************************************/






// Created 970926 by Igor Markov
// CHANGES
#ifdef _MSC_VER
  #pragma warning(disable:4786)
#endif

#include <vector>
#include "ABKCommon/abkcommon.h"
#include "linRegre.h"

LinearRegression::
LinearRegression(const std::vector<double>& x, const std::vector<double>& y):_k(0.0)
{
  abkfatal(x.size()==y.size(),
         "Attempt to compute linear regression for vectors of difft sizes \n");

  unsigned i, size=x.size();
  double   sx = 0, sy = 0;
  
  for (i=0;i!=size; i++)
  {
    sx += x[i];
    sy += y[i];
  }
 
  double sxoss = sx/size;
  double st2 = 0;
  for(i=0;i!=size;i++) 
  {
    double  t = x[i] - sxoss;
    st2   += square(t);
    _k    += t*y[i];
  }

  _k /= st2;
  _c = (sy-sx*_k)/size;
}

LinearRegression::
LinearRegression(const std::vector<unsigned>& x, const std::vector<unsigned>& y):_k(0.0)
{
  abkfatal(x.size()==y.size(),
          "Attempt to compute linear regression for vectors of difft sizes \n");

  unsigned i, size=x.size();
  double   sx = 0, sy = 0;
  
  for (i=0;i!=size; i++)
  {
    sx += x[i];
    sy += y[i];
  }
 
  double sxoss = sx/size;
  double st2 = 0;
  for(i=0;i!=size;i++)
  {
    double  t = x[i] - sxoss;
    st2   += square(t);
    _k    += t*y[i];
  }

  _k /= st2;
  _c = (sy-sx*_k)/size;
}
